The present invention generally refers to a cutting insert adapted for its mounting at a front face of a rotary cutting tool in such a manner that a clamping screw bore with which the insert is fastened to the cutting tool is directed substantially along a longitudinal axis of rotation of the cutting tool, and an operative cutting edge of the cutting insert lies substantially in a plane perpendicular to this axis, for use in such cutting operations as plunging, end milling, and the like.
A cutting insert of the above kind is described in the Applicants'co-pending Israel Patent Application No. 119557. The cutting insert is of a triangular basic shape and has upper, lower and side surfaces, the lower surface being bound by three indexable cutting edges each of which, at least partially, protrudes outwardly relative to adjacent insert corners towards an outermost extremity of the cutting edge. In addition, each cutting edge lies in a plane which passes through these corners and is inclined towards the upper surface of the cutting insert. The cutting insert is adapted for mounting on a cutting tool in such a manner that its lower surface is slightly inclined relative to a longitudinal axis of the cutting tool so as to bring the plane in which its operative cutting edge lies in a position substantially perpendicular to this axis.
When a cutting insert having the above geometry of its cutting edge is mounted in a cutting tool in the above specific manner, the insert cutting edge is provided with an appropriate relief from a face surface of a workpiece and its entire cutting edge lies in a plane parallel to this face surface, whereby a high planarity of the latter can be achieved. In addition, notwithstanding the planar geometry of the cutting edge, it can still carry out its piloting function since the central outermost point thereof is disposed ahead of the remainder of the cutting edge.
It is the object of the present invention to provide a new cutting insert having geometry of its front cutting portion specifically useful for such cutting operations as plunging at high removal rates.